


Beg the Question

by DevilOfWire



Series: DevilOfWire's Kinktober 2019 [14]
Category: Gravity Falls
Genre: Anal Gaping, Anal Sex, Asphyxiation, Begging, Bottom Dipper, Boypussy, Cock Slut, Come Inflation, Cunnilingus, Double Penetration in Two Holes, Enthusiastic Consent, Feminization, Humor, Kinktober 2019, Large Cock, M/M, One Shot, Oral Sex, Smut, Squirting, Tentacle Sex, Tentacles, Top Bill, Trans Dipper Pines, Trans Male Character, Vaginal Gaping, Vaginal Sex, Wet & Messy
Language: English
Status: Completed
Published: 2019-10-15
Updated: 2019-10-15
Packaged: 2020-12-16 20:34:37
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,673
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21042371
Author URL: https://archiveofourown.org/users/DevilOfWire/pseuds/DevilOfWire
Summary: 14. Asphyxiation | Cunnilingus | Distension | TentaclesSix years after his original trip to Gravity Falls, Dipper returns a grown man, ready for anything the place could possibly throw at him.And he meansanything.





	Beg the Question

**Author's Note:**

> **IF YOU ARE UNDER 18 DO _NOT_ READ.**
> 
> Warning for calling a trans guy's genitalia by female terms and _graphically_ (I'm not joking here) describing them! 
> 
> Here I made Dipper not have much bottom dysphoria at all and instead it's mostly top and generalized dysphoria, hence why he's perfectly fine with calling his genitals a cunt but not calling his chest or anything else by female terms. If that seems uncomfortable to you, feel free to skip this fic!

Despite it having been over half a decade since he'd last seen it, the woods are still frighteningly familiar. He recognizes almost every tree, every mark, every patch of bushes, knowing which ones to avoid for their needles and which ones are safe to fight through.

He beats through thick grass with his heart fluttering in his ribcage, already envisioning the clearing so vividly that when he bursts into it the sight is like a memory.

Sun pours through the thinning canopy of oak trees, landing on lush grass and white flowers which cover the ground.

Dipper sighs as nostalgia and bliss fill his body, walking over to the largest tree at the far side of the clearing to lean against it.

Here in this small clearing in the middle of the forest of Gravity Falls, he's truly all alone, left to his wandering imagination. He remembers that sometimes, he used to bring a book to read or a sketchpad to draw on, but right now he lets himself breathe in the fresh air, skin soaking in the dappled sunlight.

Hm, well…

He's not ever _ truly _alone though, is he?

At least not here, not in _ Gravity Falls. _

"Long time no see."

He doesn't even open his warm lids, just tilts his head, grabbing his baseball hat and dipping it in recognition. "Six years to be exact."

"What's been happ'nin', kid?"

Dipper chuckles. "Well, for starters, I'm not a kid anymore. I'm a fully fledged adult, legally _ and _personally."

Hands clap together, echoing in the valley on the cliff walls surrounding them. "That's good!"

Silence befalls them for a second, Dipper clearing his throat somewhat uncomfortably. "So, uh, what have _ you _been doing?"

"Oh, y'know, just the typical mischief stuff, nothing too bad since you've been gone though, promise!"

"No armageddons, no life-threatening catastrophes?"

"Oh no, _ no no no, _ certainly _ not!" _ Bill says a bit too quickly. "If I _ had _done it—not saying I did—surely you would've heard about it on the news, right?"

Dipper flips his hand over and back, drawing his thin lips to a tight line. "This place has a funny effect on communications, unfortunately. And I've been pretty busy in my own life, actually. No time to listen to the radio."

Bill gasps, finally spurring Dipper to peel one eye open. His demon form of a large, glowing triangle looks pretty damn uncanny against the realism of the trees behind his floating form. "No _ radio? _ How could you _ live?" _

Dipper laughs, playing with the hem of his shirt. "I almost didn't…"

"What?!" He's suddenly human before him, probably changing from sheer shock.

"Okay, maybe I'm being a bit hyperbolic. I just meant that I underwent surgery a year ago." He shrugs.

"Surgery? What in the _ hell _happened? You got in an accident or–"

"No! Just–I just…" Dipper fidgets, twirling his fingers before laying his hands out on his flat chest. "Got a couple superfluous things removed."

Bill's eyes light up as it clicks, the oft-forgotten knowledge that Dipper and Mabel are _ identical _ twins recovering itself in his brain. "Ah!" He leans on one leg, crossing his arms as he snickers lightly. "You _ do _look a pound or two lighter, Pine Tree."

"Hey!" Dipper snaps, "I went through a lot of pain and misery for you to make a joke out of this, Bill Ci–"

"I'm just joking, kid!" Bill soothes him, tilting his head, "Or should I say _ man, _ since that's apparently what you are now?"

Dipper nods. "Yeah, I like man. Not kid, not boy, _ man." _

Bill chuckles. "You're your own entire person now aren't you, Dipper? Free to come and go as you please?"

"Uh-huh!"

The demon leans slightly in, the sunlight which had previously lit his face casting a dark shadow as his hat covers his visage. "And yet you come back _ here, _ to Gravity Falls of _ all places _ in this big, wide world." He fans a hand. "What exactly is it? Does it have you in some magical bind? A dark contract, perhaps? Do you feel a–" he stretches thin air– "strange _ pull _ at night?"

Dipper just laughs. "No. If anything, it's just a little… feeling. Like, God, I don't really know how to explain it but…" He looks up to Bill with wide eyes. "When I was back in California, it might've been our _ house _ but it didn't really feel like _ home _ anymore. I missed the mermaids and the gnomes and the mystery… Only Gravity Falls has that."

"Is this your home then?"

"I… I don't know…"

Bill tuts, staring down at Dipper who looks so damn lost. He was supposed to be a man, wasn't he? No man should ever look so hopelessly confused, without even a guiding light to help him.

"How long you stayin' here?"

"At least a month."

Bill hides a smile. Plenty of time.

"Then let's figure it out together, Pine Tree!" Bill says as he brings himself down to Dipper, leaning side-by-side with him against the tree, close enough their legs brush. "We can go exploring all those old caves again, visit all those enchanted rivers and lakes, go to all the shops and see what they have, maybe get something to eat at the good old diner and then perhaps go see a movie together on the couch of whatever human abode you've found–"

"Isn't that just a date?"

Bill turns abruptly. "What?"

"Aren't you just describing, like, a date? Or maybe a few, I don't kno–"

"No!" Bill fibs, "Just activities!"

Dipper laughs, "Yeah, like, on a _ date! _ It'll be just the two of us, right?"

"Yes–"

Dipper throws his hands up, grinning. "What the fuck, man? How is it not a date?!"

Bill sours. "Just because it's two young men alone on an adventure doesn't mean they have to be romantically inclined."

" _ 'Go to the diner and see a movie together on the couch.' _ "

The demon crosses his arms. "What, does that not sound like fun?"

Dipper leans forward now, thrusting a finger against Bill's tie. "You bet it does. But it's a fucking date."

Bill sighs. "Okay, okay, fine. If that's what you wanna call it–"

Warm, actual skin of human lips shut him up.

It's just a peck, Dipper drawing back with a deep flush anyhow.

"Yeah, let's call it a date."

Bill's eyes glance about the trees before settling on his arm, holding it up to look at his wristwatch. "Oh, would you look at the space-time, I've got something _ very _important that I need to do–"

Dipper's grubby fingers smash down on his gold watch just as Bill's about to blink himself the fuck out of there. "Oh no you don't, demon!" He yanks him back to a full sit on the grass, looking sternly in his eyes.

Bill glares at him and under the heat of that demonic stare, Dipper finds himself growing suddenly bashful. "Uh, s-sorry, I just…"

Bill rolls his eyes. "Whatever could it be that you require of me, human?"

He looks over to see Dipper tucking a loose strand of hair over his ear, staring at the ground. "I uh, I've been wanting to do something with you for a while now…"

"What, and it can't wait a damn minute?"

Dipper bites his lip, meeting his gaze meekly. "I've _ really _ been wanting to do this."

"What is it then?"

The demon's gloved hand is grabbed so tentatively it annoys him, but that annoyance is quickly overcome by shock as it comes to rest on a pair of dark jeans.

Right at the crotch.

"Oh."

"Y-yeah."

A pause. Damn, Bill expected this to take at least half a year, but less than an _ hour? _ Well, he can't call Dipper a whore but…

"Do you wanna or…?"

_ "Of course!" _Bill yells before bristling as he realizes his volume. "Uh, I mean, sure."

Dipper takes Bill's hand and arranges his fingers on the button of his pants, letting the demon do the work of undoing his fly as he watches with lidded eyes.

Bill grabs the side of Dipper's jeans at either hip, tugging the attire down with his boxer-briefs.

"And you're _ completely _fine with this?"

"Uh, yeah, actually. It's kinda weird, but I really don't mind, honestly. 'S just the obvious bits that bother me."

And so Bill continues, weaving his fingers under the hem of his pants and struggling to lower them until the swell of a mound becomes visible at his centre, the ends of his thighs making a sharp V beside it.

He keeps pulling until the pants are at Dipper's mid-thighs, and as he angles his hips forward to get away from the grass, his pussy is rendered completely and utterly exposed.

Beneath his oversized clit his folds are easily visible, glistening with some natural human lubricant, pink and puffy. Absolutely wonderful.

"What do I call it?" Bill asks even as he drags his gloved fingers down his plump mound and to the very top of his cunt.

"Pussy, cunt, hole, cocksheath, I don't care," Dipper manages to say with foreign fingers beginning to swirl over his clit, obviously much bigger than that of a typical female's for the testosterone in his blood which he painstakingly injects himself with once a week.

"Well, Dipper," Bill mutters, bringing his glove tips to his mouth to lick and wet them, tasting some tang of cum as he does so, "you have a lovely _ cunt." _

Dipper whines at that as well as the slick fingers which massage up and down his swollen clit, easily bringing entire stunning flashes of pure pleasure with just the slightest movement up or down, side to side. He's always been incredibly sensitive, but the T only exaggerated that a thousand-fold.

Bill chuckles as the human moans mere seconds after initial contact, letting his hand move naturally down to between Dipper's labia, finding the hole between them and rubbing against its wet entrance.

Dipper shudders a moan above him, grabbing the outside of his bare thighs and spreading them open as far as his jeans pooled around his legs allow.

He cries out when Bill thrusts two long fingers inside, gloves catching on his walls and adding to the delicious friction, making him double over and grab onto Bill's shirt only to feel him slipping away.

He opens his eyes fully, watching as Bill lowers his entire body, still twisting his fingers inside of him.

_ "Ah, fuck!" _ Dipper yells before slapping a hand over his mouth, forced to listen to his own depraved voice echo around the valley for a whole second. "Ah, _ Bill _…" he whimpers, looking down to watch Bill's hair wave in the wind just above his lap, feeling his deft tongue work on his clit.

He reaches behind himself and rips his nails into the bark of the tree. _ Fuck, _ he's never even had someone _ touch _him at all before, and now he's getting eaten out? This demon would truly be the death of him.

His tongue edges his clit, eliciting shock waves of pleasure up Dipper's spine before shifting down to join his fingers inside of him, lapping up the cum which he spills readily just at watching his head move atop his thighs.

He moves out with one last twirl to Dipper's twitching clit, lips soaked in saliva and slick, continuing to thrust his fingers slightly. "Wanna try something else, Pines?"

Dipper blinks blearily at him. What in the world else could he possibly do to him? "Huh?"

From beneath his cape slides a black thing, looking like a long arm–no–a tentacle, slicking black goo onto the grass as it moves further into reality from God-knows-where. The tentacle's tip moves up and down as if in greeting.

"That."

Dipper frowns slightly. "What are you going to do with… _ that?" _

"Whatever you're willing to do. Could just hold your hand, could wrap around your chest, rub your clit, fuck you in either of your holes, maybe even strangle you." Bill shrugs. "Whatever you want."

Dipper just sits in stunned silence, eyes wide.

That is, until Bill strokes his fingers right against his G-spot, making him keen back to reality.

"Fuck! Uh, I don't–any."

"Any?"

"Anything. Just… start slow… please."

Bill smiles. "Happy to oblige."

And so the tentacle lunges forward, curling around Dipper's palm and absolutely coating it in a strange inky black substance which stains as it moves, leaving so much of it that it gets very ridiculous very quickly. What fucking dimension had enough room for this sheer volume of tentacle cum?

"More?"

Dipper nods, albeit slightly off-put by the cool, slimy goo the tentacle leaves behind as it slides up his arm.

It enters the arm of his shirt, moving round his back and he'd be highly uncomfortable if it weren't for Bill's fingers still stuck up his cunt, fucking him regularly.

The tentacle tickles his side before coming to his front, gracing over the mostly healed scars upon it before making its way around him again. It coils again and again, wrapping him up in meters of pure tentacle, and he wonders again what that dimension Bill's pulling this thing from looks like. What a fucking nightmare.

And then, just as Bill runs his thumb over Dipper's clit right on the most sensitive part of his hood, the tentacle tightens, compressing his chest so he finds it harder to breathe, the sensation uncomfortable and restricting but not painful, not yet.

"More?"

"Y-yes."

So the tentacle yanks harder on his ribcage, now pressing enough to really _ hurt, _ his breaths coming ragged and far between. His vision darkens even though his eyes widen, the effects of asphyxiation beginning to dawn on him.

The tentacle relaxes, allowing him to heave in pants, dark spots in his vision filling back in with greens and yellows.

Bill tuts, thrusting his fingers into Dipper's cunt up to the knuckle, "I'm sorry, was that too much?"

"N-no! It was… nice, actually. Or, it was beginning to be."

Bill chuckles. "You want more then, I take it."

"Mhm."

Dipper relaxes after a few seconds when he feels himself _ not _ be crushed once again, expecting the tentacle to move away so it can play at his nether regions.

Instead, the tentacle remains, dripping slime down his sides and soaking through his shirt as a twin appears from behind Bill, snaking its way above Bill's hand to rub its thin tip around his clit.

_ "Ah!" _Dipper screams before the tentacle around his chest constricts to the point it was at before, increasing as he watches Bill's inactive hand form into a fist and tighten.

The pressure continues, spots coming back to his eyes and bleeding life away from him, a heady high coming to his head and leaving his thoughts slow and nearly incomprehensible after a while.

He can barely focus on anything at all, not his surroundings, not the disgusting squelching sounds of his pussy, just the immediate feelings on his body. The tentacle on his cunt continues to flick against him, wrapping its thin end around his bud and squeezing just enough that it makes him try to shriek, ultimately unable to for his breathlessness.

His legs shake on the ground, thigh muscles straining as he nears orgasm, arching his back and rolling his hips into Bill's thrusting fingers.

And then it all stops.

The sharp breath he takes in destroys all of his progress to his climax, like a bucket of cold water as he's brought back yet again to harsh reality.

He looks down to see his upper and lower body coated in the black substance, the grass beneath his ass becoming black like tar with every passing second.

"Fuck," Dipper breathes as he looks in Bill's smug eyes, "th-that was amazing."

"Even more?"

He nods.

Bill chuckles, and with a flick of his index finger, the tentacle on his clit moves down into his hole, replacing Bill's fingers like an Indiana Jones trick and then some, slithering inside of his cunt all the way to the end of his tunnel, tickling his cervix, going so far as to try to slide its tiny point into the microscopic hole in it.

His entrance is stretched on the steadily thickening girth of the tentacle, enough that it almost hurts and stretches his clit in turn, making him groan.

It draws out of him slowly before slamming back in, making his head hit the tree hard as his nub is fucked against as well. It drills him steadily in that exact way for a minute or two, the immense fullness from the tentacle making his toes curl.

The one about his chest draws up to play with one of his nipples, flicking it and making it even harder with the wetness it's soaked with.

"Ah, ah, B-Bill," Dipper starts to chant, overcome with pleasure as his hips twist on the soiled grass, "g-gonna c-cum! Hah–"

The tentacle rips out of him, bringing with it litres of cum both human and other, ruining the grass even further.

"Bill!" Dipper cries before he's hushed by a pair of lips.

"It's okay, Pine Tree," he says, moving his hands down to undo his belt, "we'll get you there together!"

He drops his pants and boxers, revealing his thick cock just a little too large to be naturally human. The sight of it makes Dipper's mouth water anyway, his legs spreading subconsciously, drawing chuckles from Bill as he saddles up to him.

He reaches down to his cock to guide it to Dipper's slightly gaping entrance, looking him in the eyes. "Ready?"

Oh God, was he really about to let his virignity be taken by a fucking demon? He should really think befor–

"Yes!"

Bill grins, "You got it!"

He fucks into him in one hard move, Dipper slamming against the tree from the force and clawing at Bill's back as pleasure and pain fill his senses all at once.

Bill's so fucking _ huge, _similar to the base of the tentacle but that way the entire length but for his cockhead, forcing Dipper's insides to adjust quickly, his clit stimulated the entire long draw of Bill's cock out of his cunt, white-hot pleasure blinding his vision when Bill slams back in.

Dipper looks down and literally _ gasps _ as he sees some movement in his lower abdomen, reaching down to lift his shirt hem to double-check. Yes, yes, holy _ fuck, _ somehow Bill was so fucking big he was actually moving his insides, visible through all of his viscera and skin, a small but obvious bump moving up and down in his belly as Bill fucked in and out.

God, he didn't even know _ why _ but that was so fucking _ hot. _

The tentacle around his chest constricts teasingly, just a slight sensation of touch for the moment. What really makes Dipper's eyes widen as Bill continues to take him ruthlessly is the dual sensations of a slimy tentacle both on his asshole and his neck, just tickling his flesh.

Bill leans in to Dipper's ear, voice dripping lust as he rumbles deeply, inhumanly, _ "More?" _

Dipper doesn't even think. "Yes, yes, _ yes!" _

It all happens at once. His asshole is breached by the tip of the wet tentacle at his bottom which had fucked his cunt earlier; the one about his chest tightening to a vice until he can't draw even the slightest of wheezes; and his neck squeezing as it's crushed by a similar thing, pressing down on his trachea, making him unable to even swallow.

He's in a complete state of euphoria, the world entirely forgotten, just feelings, pleasure, pain, white, black, absolutely breathless.

He cums when Bill fucks into him one last time, simply unable to take anymore, having been wound tight like a spring until he finally snaps, orgasming harder than he ever had in his life _ put together. _ The pressure of everything persists for a moment as he distantly feels something leaking out of him, too high to be his cunt, too low to be any of the tentacles.

The tentacles strangling him let him go and as he sputters in breath he realizes what happened, seeing Bill's cock coated in copious amounts of watery, clear cum.

He fucking _ squirted. _

Bill thrusts into him a few more times, the tentacle in his ass mirroring his actions and stretching that hole just as wide before Bill cums, shooting semen into his tight pussy.

The sperm that leaks out of Dipper's abused hole looks human enough, white and sticky, but he soon learns that even this isn't truly human of Bill. Because he just keeps fucking cumming, shooting more and more litres of hot cum right into his cunt until it has absolutely no where to go but into his cervix or out of his pussy to leak down his taint and onto the grass.

The bulge in Dipper's stomach from Bill's sheer size increases slowly but steadily, his uterus filling with ungodly amounts of semen that it distended enough to show through his skin.

Thank fucking _ God _ he couldn't get pregnant, because he'd be _ fucked. _

The slimy tentacles finally withdraw into Bill's cloak, the only trace of their existence the ridiculous amounts of black gooey slime which cover Dipper's entire exhausted body, more of him wet than dry at this point.

"That was fun, Pine Tree!"

Dipper looks up at Bill, wincing as he removes his cock from his ruined cunt, a mix of white and black cum ejecting from both of his orifices. He puffs, "Says you. You're not the one who just got fucked within an inch of his life!"

Bill turns his hands up. "You're the one who asked for it!"

Dipper shakes his head, wrapping his arms around Bill's nape to press him closer. "I know I am, idiot."

He forces their lips together, letting it last long enough until he's out of breath.

Dipper smiles, whispering in his ear lightly, "Okay, we can go on a date now."

Oh God, Bill wasn't ready for this.

**Author's Note:**

> * * *
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> I am open to any sort of comments if you wanna, including criticism. ;] If not, kudos are also lovely! :D Ty for reading! 
> 
> Btw I know the twins were supposed to revisit Gravity Falls the next summer, I guess in this story they just didn't for some reason? More dramatic I dunno lol.


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